MULTIPLE
CHOICE. Choose the one alternative that
best completes the statement or answers the question.

1) Which
of the following is closest in mass to a white dwarf?

A) the Moon B)
the Earth C) Jupiter D) the Sun

2) Suppose a white dwarf is gaining mass because
of accretion in a binary system. What happens if the mass someday reaches the
1.4-solar-mass limit?

A) The white dwarf
undergoes a catastrophic collapse, leading to a type of supernova that is
somewhat different from that which occurs in a massive star but is comparable
in energy.

B) The white
dwarf, which is made mostly of carbon, suddenly becomes much hotter in
temperature and therefore is able to begin fusing the carbon. This turns the
white dwarf back into a star supported against gravity by ordinary pressure.

C) The white dwarf
immediately collapses into a black hole, disappearing from view.

D) A white dwarf
can never gain enough mass to reach the limit because a strong stellar wind
prevents the material from reaching it in the first place.

3) Which of the following statements about novae
is not true?

A) A star system
that undergoes a nova may have another nova sometime in the future.

B) A nova involves
fusion taking place on the surface of a white dwarf.

C) Our Sun will
probably undergo at least one nova when it becomes a white dwarf about 5
billion years from now.

D) When a star system
undergoes a nova, it brightens considerably, but not as much as a star system
undergoing a supernova.

E) The word nova
means "new star" and originally referred to stars that suddenly
appeared in the sky, then disappeared again after a few weeks or months.

4) What kind of pressure supports a white dwarf?

A) neutron
degeneracy pressure

B) electron
degeneracy pressure

C) thermal
pressure

D) radiation
pressure

E) all of the
above

5) Which of the following is closest in size
(radius) to a white dwarf?

A) the Earth

B) a small city

C) a football
stadium

D) a basketball

E) the Sun

6) After a massive star supernova, what is left
behind?

A) always a white
dwarf

B) always a
neutron star

C) always a black
hole

D) either a white
dwarf or a neutron star

E) either a
neutron star or a black hole

7) Which of the following is closest in size
(radius) to a neutron star?

A) the Earth

B) a city

C) a football
stadium

D) a basketball

E) the Sun

8) What causes the radio pulses of a pulsar?

A) The star
vibrates.

B) As the star
spins, beams of radio radiation sweep through space. If one of the beams
crosses the Earth, we observe a pulse.

C) The star
undergoes periodic explosions of nuclear fusion that generate radio emission.

D) The star's
orbiting companion periodically eclipses the radio waves emitted by the main
pulsar.

E) A black hole
near the star absorbs energy and re-emits it as radio waves.

9) What is the basic definition of a black
hole?

A) any compact
mass that emits no light

B) a dead star
that has faded from view

C) any object from
which the escape velocity equals the speed of light

D) any object made
from dark matter

E) a dead galactic
nucleus

10) Which
of the following statements about black holes is not true?

A) If you watch
someone else fall into a black hole, you will never see him or her cross the
event horizon. However, he or she will fade from view as the light he or she
emits (or reflect) becomes more and more redshifted.

B) If we watch a
clock fall toward a black hole, we will see it tick slower and slower as it
falls nearer to the black hole.

C) A black hole is
truly a hole in spacetime, through which we could leave the observable universe.

D) If the Sun
magically disappeared and was replaced by a black hole of the same mass, the
Earth would soon be sucked into the black hole.

E) If you fell
into a black hole, you would experience time to be running normally as you
plunged rapidly across the event horizon.

11) What do we mean by the singularity of a
black hole?

A) There are no
binary black holes each one is isolated.

B) An object can
become a black hole only once, and a black hole cannot evolve into anything
else.

C) It is the center
of the black hole, a place of infinite density where the known laws of physics
cannot describe the conditions.

D) It is the edge
of the black hole, where one could leave the observable universe.

E) It is the
"point of no return" of the black hole; anything closer than this
point will not be able to escape the gravitational force of the black hole.

12) If you were to come back to our Solar System
in 6 billion years, what might you expect to find?

A) a red giant
star

B) a white dwarf

C) a rapidly
spinning pulsar

D) a black hole

E) Everything will
be pretty much the same as it is now.

13) What is the thickness of the disk of the Milky
Way?

A) 100 light years

B) 1,000 light
years

C) 10,000 light
years

D) 100,000 light
years

E) 1,000,000 light
years

14) What is the diameter of the disk of the Milky
Way?

A) 100 light years

B) 1,000 light
years

C) 10,000 light
years

D) 100,000 light
years

E) 1,000,000 light
years

15) What kinds of objects lie in the disk of our
galaxy?

A) open clusters

B) O and B stars

C) old K and M
stars

D) gas and dust

E) all of the
above

16) What makes up the interstellar medium?

A) open clusters

B) O and B stars

C) K and M stars

D) gas and dust

E) all of the
above

17) How does the interstellar medium obscure our
view of most of the galaxy?

A) It produces so
much visible light that it is opaque and blocks our view of anything beyond it.

B) It reflects
most light from far distances of the galaxy away from our line of sight.

C) It absorbs all
wavelengths of light.

D) It absorbs
visible, ultraviolet, and some infrared light.

E) all of the
above

18) Harlow Shapley concluded that the Sun was not
in the center of the Milky Way Galaxy by

A) looking at the
shape of the "milky band" across the sky.

B) mapping the
distribution of stars in the galaxy.

C) mapping the
distribution of globular clusters in the galaxy.

D) mapping the
distribution of gas clouds in the spiral arms.

E) looking at other
nearby spiral galaxies.

19) Approximately how far is the Sun from the
center of the galaxy?

A) 28 light-years

B) 280 light-years

C) 2,800
light-years

D) 28,000
light-years

E) 28 million
light-years

20) Where are most heavy elements made?

A) in the
interstellar medium

B) in stars and
supernovae

C) in the Big
Bang, when the universe first began

D) none of the
above

E) all of the
above

21) What is the most common form of gas in the
interstellar medium?

A) molecular
hydrogen

B) molecular
helium

C) atomic hydrogen

D) atomic helium

E) ionized
hydrogen

22) What produces the 21-cm line that we use to
map out the Milky Way Galaxy?

A) atomic hydrogen

B) ionized
hydrogen

C) molecular
hydrogen

D) carbon monoxide

E) helium

23) Compared
with our Sun, most stars in the halo are

A) young, red, and
dim and have fewer heavy elements.

B) young, blue,
and bright and have much more heavy element material.

C) old, red, and
dim and have fewer heavy elements.

D) old, red, and
dim and have much more heavy element material.

E) old, red, and
bright and have fewer heavy elements.

24) Approximately how long does it take the Sun to
orbit the Milky Way Galaxy?

A) 23,000 years

B) 230,000 years

C) 2.3 million
years

D) 230 million
years

E) 23 billion
years

25) Why do we believe 90% of the mass of the Milky
Way is in the form of dark matter?

A) The orbital
speeds of stars far from the galactic center are surprisingly high, suggesting
that these stars are feeling gravitational effects from unseen matter in the
halo.

B) Although dark
matter emits no visible light, it can be seen with radio wavelengths, and such
observations confirm that the halo is full of this material.

C) Theoretical
models of galaxy formation suggest that a galaxy cannot form unless it has at
least 10 times as much matter as we see in the Milky Way disk, suggesting that
the halo is full of dark matter.

D) Our view of
distant galaxies is sometimes obscured by dark blotches in the sky, and we
believe these blotches are dark matter located in the halo.

26) Where does most star formation occur in the
Milky Way today?

A) in the halo

B) in the bulge

C) in the spiral
arms

D) in the Galactic
center

E) uniformly
throughout the Galaxy

27) What
evidence supports the theory that there is a black hole at the center of our
galaxy?

A) We observe an
extremely bright X-ray source at the center of our galaxy.

B) We can see gas
falling into an accretion disk and central mass at the center of our galaxy.

C) The motions of
the gas and stars at the center indicate that it contains a million solar
masses within a region only about 1 parsec across.

D) We observe a
large, dark object that absorbs all light at the center of our galaxy.